RAM Latency Calculator - CAS latency in ns
Compare DDR kits by true CAS latency: MT/s and CL to nanoseconds.
Compare DDR kits by true latency
- Type the transfer rate in MT/s exactly as printed on the kit or the store listing — for example 3200, 3600 or 6000. This counts transfers per second, not the clock in MHz.
- Type the CAS latency in cycles (CL), for example 16 or 30, and rename each kit so the table stays readable.
- Worked example: 3200 MT/s with CL16 gives 16 × 2000 ÷ 3200 = 10 ns. A 3600 MT/s kit with CL16 gives 16 × 2000 ÷ 3600 ≈ 8.89 ns — about 11% lower latency for the same CL number.
- Pick which kit is the base of the comparison. The table shows every other kit as a signed percent difference, and the bar chart ranks kits from lowest latency upward.
- Open the advanced timings to convert tRCD, tRP and tRAS into nanoseconds at the same rate. Each timing stays in its own column by design.
- Choose the total data-bus width for the theoretical bandwidth, then copy the text summary or copy a link that reopens the same four kits.
RAM latency questions
Why MT/s and not MHz?
DDR moves data twice per clock cycle, so a 3200 MT/s kit runs on a 1600 MHz clock. Calling the transfer rate “MHz” doubles the real clock. This tool labels the rate correctly and derives the clock as MT/s ÷ 2 and the cycle as 2000 ÷ MT/s nanoseconds.
How can CL30 be as fast as CL16?
Cycles alone say nothing: latency in nanoseconds is CL × 2000 ÷ MT/s. DDR5-6000 CL30 gives 30 × 2000 ÷ 6000 = 10 ns — exactly the same as DDR4-3200 CL16. Always compare the nanoseconds column, never the CL number on its own.
Why not add tRCD + tRP + tRAS into one latency?
Different memory accesses walk through different steps, so a single sum would describe no real operation. The calculator converts each timing to nanoseconds side by side, which is the honest way to compare two kits.
Is the bandwidth in GB/s or GiB/s?
Decimal GB/s: MT/s × bus bits ÷ 8 ÷ 1000. A 3200 MT/s kit on a 64-bit bus gives 25.6 GB/s. Enter the aggregate bus width a single time — the tool never duplicates channels or DDR5 subchannels behind your back.
Will lower CAS latency raise my FPS?
Not predictably from these numbers alone. Games depend on the CPU, GPU, resolution and the whole timing set, not just CAS. Use this page to compare kits fairly, not to promise frame rates.